To the Editor:—
A 32-yr-old gravida 2, para 1 woman underwent uneventful placement of an epidural catheter at L3–L4. A bolus of 10 ml bupivacaine, 0.25%, was given incrementally, without adverse effect. A member of the anesthesia care team primed the epidural tubing (primary IV Plumset; Hospira Inc., Lake Forest, IL; Convertible Pin 107 inch with option lock) with 0.0625% bupivacaine containing 2 μg/ml fentanyl (250 ml bag total). The epidural tubing was inserted into an Abbott Labs Micro/Macro PlumXL infusion pump (Abbott Park, IL). No filter was used between the epidural catheter and tubing. Approximately 2 h after epidural insertion and pump hookup, the patient called the nurse and reported difficulty with breathing and numbness of the chest. On physical examination, the patient was observed to have good grip strength, a T4 sensory level to cold test, and blood pressure within normal limits. There were no fetal heart rate abnormalities.
It was observed that the epidural infusion bag was empty and that both the flow regulator and the door on the infusion pump were in the open position. Epidural infusion was temporarily suspended, and the mother delivered a healthy baby, with no adverse sequelae.
The situation noted seems to be due to an interaction between a human error and the design of the infusion pump—an error that might be avoided by changes in the design of the device. Specifically, human error might be avoided if the cassette device were designed so that the flow regulator must be in the closed position when it is inserted into the pump. Also, the flow regulator might be designed with a spring that automatically retracts inward after priming. In lieu of a design change, we attached a notice regarding proper use on each pump, and all members of the care team were reeducated regarding safe and proper use of an infusion pump.
This case underscores the inherent safety of using low-dose local anesthetic for continuous epidural infusion. If a more concentrated solution had been used, a potentially more adverse outcome might have occurred. With a free drip system, gravity determines how fast an infusion occurs. The height of the epidural bag thus determines the rapidity of infusion.
*Saint Barnabas Medical Center, Livingston, New Jersey. firstname.lastname@example.org